Updating universe in cluster environment

Hi,

I have a clustered BO XIR3.1 environment with two servers BO1 and BO2.

During my initial deployment, I imported the biar files to BO1 server and when attempt to open a webi Template, it returns an error saying the universe is not found. To resolve, I imported the biar into the BO2 server. (Note sure if this is the correct method).

Next, I try to make some modification to the universe with designer logged on to BO1. I make the update and then imported the universe. After some days, when I exported back the universe, I realised it has reverted to the original universe. Does that means that during updates, I need to perform on both servers or may i missing some configurations?

Thanks.